4- respiratory of ILD

Question 1

what is interstitial lung disease (ILD)?

Answer 1

a heterogenous group of disorders, characterised by inflammation + fibrosis occuring interstitial of lung

Question 2

what is pulmonary interstitium?

Answer 2

supporting connective tissue that lies between or around functional cells or structures of the organ

in lungs = forms walls of alveolar walls. composed of collagen, elastin and capillaires

Question 3

what is early stage ILD called?

Answer 3

alveolitis

Question 4

what is characterisations of late stage ILD?

Answer 4

fibrosis (scarring) and eventual honeycombing

Question 5

what functional reductions occur as a result of ILD?

Answer 5

• Reduction in diffusion capacity
• Reduction in lung volume
• Reduction in lung compliance

Question 6

what are clinical effects of ILD?

Answer 6

hypoxia, respiratory failure, secondary pulmonary hypertension and right-sided heart failure

Question 7

what are some causes of ILD?

Answer 7

= things that can cause inflammation + fibrosis
- can be due to environmental stimuli e.g. minerals, drugs, radiation, mechanical ventilation
- can be hypersensitivity reactions e.g. proteins in animals, mouldy hay

often idiopathic e.g. connective tissue disease, IPF

Question 8

how does ILD lead to inflammation and fibrosis?

Answer 8

= acting along with host factors →damage to epithelium (induce inflammatory response) - prolonged or repeated triggers = fibrosing, fibroblasts recruited

Question 9

how can you obtain tissue for histological examination?

Answer 9

by transbronchial biopsy (less invasive but yields less tissue) or thoracoscopic VAT (more invasive but more reliable tissue yield + larger samples)

Question 10

what are examples of ILD?

Answer 10

• Usual interstitial pneumonia (pathological name for IPF = type of idiopathic interstitial pneumonia)
• Connective tissue disease-associated ILD
• Pneumoconiosis (known cause, has subtypes silicosis etc)
• Sarcoidosis (granulomatous ILD)
• Hypersensitivity pneumonitis (known cause)

Question 11

what is usual interstitial pneumonia?

Answer 11

UIP is the pathological term; idiopathic pulmonary fibrosis (IPF) is the corresponding clinical term

Question 12

what is idiopathic pulmonary fibrosis? (IPF)

Answer 12

• most common type of ILD
  Characterised by progressive pulmonary fibrosis leading to respiratory failure. nasty disease with only 3-5 years to live (debilitating, progressive)
  = unknown cause

pathological term = usual interstitial pneumonia (UIP)

Question 13

what are characteristic features of interstitial pulmonary fibrosis (IPF)?

Answer 13

patchy interstitial fibrosis

Question 14

what region of the lungs does interstitial pulmonary fibrosis (IPF) occur?

Answer 14

Occurs mostly in the basal region of the lower lobes, in a subpleural and para-septal distribution

Question 15

what are early lesions in interstitial pulmonary fibrosis (IPF)?

Answer 15

• characterised by Fibroblastic foci (areas of active fibrosis where fibroblast proliferation and collagen deposition)
• overtime as disease progresses, fibroblast (cells that produce collagen) decrease in number but amount of collagen continues to increase leading to development of late lesions

Question 16

what are late lesions in IPF?

Answer 16

= honeycombing look on histology

• Dense fibrosis
• Destruction of alveolar architecture – cystic spaces lined by hyperplastic type 2 pneumocytes or bronchiolar epithelium

Question 17

what connective tissue diseases are associated with ILD?

Answer 17

connective tissue diseases = immune system attacks own body →inflammation + tissue damage

• rheumatoid arthritis
• systemic lupus erythematosus (SLE)
• systemic sclerosis
• dermatomyositis
• polymyositis

Question 18

what are clinical features of connective tissue disease associated ILD?

Answer 18

• Interstitial fibrosis
• Pleuritis and pleural effusions
• Rheumatoid nodules (in rheumatoid arthritis)

Question 19

where do rheumatoid nodules occur?

Answer 19

rheumatoid nodules can occur in various sites, commonly subcutaneously (only in people with rheumatoid arthritis)

Question 20

what are histological characteristics of rheumatoid nodules?

Answer 20

three distinct zones are observed in well-developed rheumatoid nodules:

(1) a central zone of fibrinoid necrosis
(2) a middle zone of palisading histiocytes
(3) a peripheral zone of highly vascularized granulation tissue with a chronic, mononuclear inflammatory cell infiltrate

Question 21

what is pneumoconiosis?

Answer 21

Lung disease caused by reaction to inhaled mineral dust, organic and inorganic particles, chemical fumes and vapours (usually in occupational setting)

Question 22

what are examples of pneumoconiosis?

Answer 22

• Coal workers’ pneumoconiosis
• Silicosis
• Asbestosis
  →they sometimes take long time to develop, have had these exposures decades ago

Question 23

what does development of pneumoconiosis depend on?

Answer 23

• concentration + duration of exposure
• particle size of material (1-5 microns = most dangerous, tiny as get into alveoli and cause inflammatory + fibrotic reaction)
• solubility + reactivity of particles
• clearance of particles
• host response

Question 24

what is silicosis?

Answer 24

type of pneumoconiosis caused by inhalation of proinflammatory crystalline silicon dioxide (quartz) from hard rock mining, stone cutting etc
= make hard collagenous scars in lungs which may develop progressive massive fibrosis

Question 25

what is asbestosis?

Answer 25

fibrotic disease caused by asbestos, type of pneumoconiosis

Question 26

what does asbestosis look like in histology?

Answer 26

• Parenchymal interstitial fibrosis
• Pattern of fibrosis similar to UIP (fibroblastic foci and variable fibrosis)
• Presence of asbestos bodies – asbestos fibres coated with iron-containing proteinaceous material (also called ferruginous bodies)

Question 27

what are asbestos related diseases?

Answer 27

• Pleural plaques
• Recurrent pleural effusions
• Interstitial fibrosis (Asbestosis)
• Lung carcinoma
• Mesothelioma

Question 28

what is sarcoidosis?

Answer 28

systemic granulomatous ILD disease of unknown aetiology

= affects lung & hilar lymph node, eyes, skin etc

you diagnose by ruling out other causes of granulomatous inflammation (TB, fungal infections etc)

Question 29

what are the granulomas like that are formed in sarcoidosis?

Answer 29

well-formed, non-caseating (non-necrotising) often with multinucleated giant cells

• distributed along lymphatics around bronchi + blood vessels
• granulomas in lung often heal - varying degrees of fibrosis and hyalinization

Question 30

what is hypersensitivity pneumonitis?

Answer 30

• Spectrum of immunologically induced interstitial inflammatory lung disorders caused by exposure to inhaled antigens (they have hypersensitivity to causative agent)
• (Antigens like spores of thermophilic bacteria, fungi, animal proteins, bacterial products)

Question 31

what happens in hypersensitivity pneumonitis?

Answer 31

acute exacerbation initially, prolonged exposure chronic disease can develop and chronic interstitial fibrosis may lead to respiratory failure
→Progression can be prevented by removal of the causative antigen

Question 32

what is histology for hypersensitivity pneumonitis?

Answer 32

• Airway centred disease (peribronchiolar)
• Interstitial inflammatory infiltrate - lymphocytes, plasma cells, macrophages
• Loosely-formed, non-caseating granulomas
• Interstitial fibrosis – fibroblastic foci, obliterative bronchiolitis, honeycombing

Question 33

what are common clinical presentations of IPF?

Answer 33

• Bibasal fine end-inspiratory crackles
• Finger clubbing